Domestic pets, particularly cats, typically utilize a litter box for their waste needs. Such litter boxes fall into two categories, the totally manual pan or container which carries a quantity of litter and the automatic or self-cleaning variety, which also carries a quantity of litter. The present invention pertains to the latter category and the patent literature does include a variety of such devices. U.S. Pat. No. 6,568,348, for instance, is directed to a circular litter device that extracts waste from litter material by rotating a rake or the chamber. Due to rotation of the rake or chamber, solid waste is extracted from the litter material using tines, and such waste is pushed to the outer perimeter of the chamber. The curvature of the rake allows the rake to cooperate with a scoop, which simultaneously removes solid waste from the rake and retracts into a tunnel, as the rake passes thereby.
U.S. Pat. Nos. 6,401,661 and 6,234,112 are both directed to a self-cleaning pet litter box. The pet litter container is rotatably mounted on a base member, and rotates to move the pet litter over a sieve. The sieve is ramped shaped and therefore, clumped portions of the pet litter that are not sifted through its openings are forced upwardly toward a conveyer. The conveyer serves to carry the clumped portions of pet litter away from the pet litter container.
U.S. Pat. No. 6,286,459 is directed to a litter container with a rotary movement sieve. The sieve is attached to a rotatable ring around the upper portion of a container. As the sieve rotates, clumped portions of solid waste are captured thereon. Since the sieve is removable, the sieve, and the clumped portions of solid waste can be removed from the container.
U.S. Pat. Nos. 6,082,302 and 5,447,812, are both directed to a rectangular litter device that extracts waste from litter material using a comb that traverses the pan lengthwise, eventually conveying waste clumps into a receptacle at the front of the device.
U.S. Pat. No. 4,574,735 is directed to a circular litter device that extracts waste from litter material using a rake which sweeps through a circular chamber. In this device, the waste material is deposited into a container which is rotated to sanitize and deodorize the contents.
The foregoing automatic litter devices have provided a variety of styles and mechanisms to facilitate periodic cleaning of the litter. Nonetheless, the apparatus of the present invention provides a novel approach to the design and operation of such devices by providing a single drive mechanism for the operation of all moving elements as well as other features not present in combination in a single device heretofore.